Plastic container



P 1963 J. D. BOSTROM 3,104,776

PLASTIC CONTAINER Filed Sept. 6, 1961 INVENTOR: JOHN DONALD OSTROMATT'YS United States Patent ()fiice 3,104,776 Patented Sept. 24, 19633,104,776 PLASTIC CONTAINER John Donald Bosh-om, Niles, IiL, assignort'o Poster Packaging, Inc, Chicago, Iii, a corporation of Delaware FiledSept. 6, 1961, Ser. No. 136,263 8 Claims. (Cl. 220-72) This inventionrelates to a plastic container and more particularly to a plasticcontainer made out of a self-sustaining, relatively rigid, resilient,distortable plastic material so constructed as to resist distortion atthe corners.

It is well known to make containers out of self-sustaining, relativelyrigid plastic materials, such as, for example, oriented polystyrene.This type of material is readily distorted but will normally tend toreturn to its original position due to its inherent resiliency. However,when containers constructed from this material have corners andespecially rounded corners, the material at the corners does not returnto its initial position very readily after it has been pressed inwardly.This is a decided disadvantage, particularly in containers which areused to package foods and where it is desirable that the container havea pleasing appearance. A dented container frequently arouses thesuspicion of the customer that the container and its contents have beenmishandled. Even where the container has not been dropped or otherwisemishandled it is easily possible for the customer to press the cornersinwardly and leave the container in this shape so that the next customerwill think that it has been dropped.

One of the objects of the present invention is to provide a new andimproved container of self-sustaining, relatively rigid, resilient,distortable plastic material having 1 corners which when pressedinwardly tend to restore to their initial positions.

Other objects of the invention will be apparent from the followingdescription in conjunction with the accompanying drawings in which:

FIGURE 1 represents a bottom plan view of one embodiment of a plasticcontainer made in accordance with this invention;

FIGURE 2 represents a sectional view with parts broken away of thecontainer shown in FIGURE 1 taken along the line 2-2 of FIGURE 1;

FIGURE 3 represents a bottom plan view of another embodiment of acontainer provided in accordance with the invention;

FIGURE 4 represents a partial sectional view of the container shown inFIGURE 3 taken along the line 4-4 of FIGURE 3;

FIGURE 5 is a plan sectional view taken along the line 55 of the portionof the container shown in FIG- URE 4;

FIGURE 6 is a plan sectional view taken along the line 66 of the portionof the container shown in FIG- URE 4; and

FIGURE 7 is a bottom plan view of the portion of the container shown inFIGURE 4.

As will be seen from the drawings, the invention provides a container ofself-sustaining, relatively rigid, resilient, distor-table plasticmaterial comprising a bottom and wide walls extending upwardly from saidbottom, corners formed between adjacent side walls of said container,and indentations formed in said corners whereby when said corners arepressed inward-1y they will tend to restore to their original positions.The side walls are preferably inclined outwardly and the corners arepreferably rounded or generally rounded as shown in the drawings. Theside walls also preferably contain grooves or corrugations whichincrease the strength and rigidity.

These grooves preferably run from the top to a point near the bottom ofthe container in the manner shown in the drawings. This structure of thecontainer does not form a part of the invention. The bottom of thecontainer may be flat, inverted upwardly or oifset downwardly withrespect to the side walls.

In FIGURE 1 the container 1 consists of a single piece ofself-sustaining, relatively rigid, resilient, transparent, distortableplastic material, such as oriented polystyrene, which is made by aspecial process in which the polystyrene sheet is stretched. The upperpart of the container :1 is provided with a substantially horizontalflange 2 which can form a sealing portion for a sheet of plasticmaterial or other suitable cover for the container. The side walls 3, 4,5 and 6 extend from the flange portion 2 to the bottom 7. Theintermediate" portions of the side walls are shaped in the formation ofthe container by molding, stamping, or otherwise, to provide grooves orcorrugations as shown at 8 in FIGURE 2 which extend from the top of thecontainer to a point adjacent the bottom thereof and serve to increasethe rigidity of the side walls. Heretofore, where containers of thistype have been made with such reinforcing grooves or corrugations, ithas been customary to make the corners rounded without any grooves. Thisresults in a container in which the corners are readily distorted and donot recover from the distortion, particularly when the container isfilled and sealed.

In the practice of this invention it has been found that by providing aninwardly extending groove or indentation at the corners as shown by thegrooves 9, '10, 11 and 12, it is possible to make a container in whichthe corners, after being pressed inwardly, will tend to restore to theiroriginal positions. The grooves or indentations 9, 10, 11 and12preferably extend in a line substantially bisecting the corners andpreferably run substantially from top to bottom of the container.

In addition to the indentation at the corners it is also desirable toprovide inwardly extending adjacent grooves spaced from the cornergroove in the adjacent side walls and running from the top toward thebottom of the container but curving away from the corner groove towardthe bottom of the container. Such indentations are shown in FIGURE 1 bythe numerals 13, 14, 15, 16, 17, 18, 19 and 20. These curvedindentations further assist in restoring the corners after they havebeen pressed inwardly, especially containers having generally roundedcorners, such as shown in the drawings.

The container shown in FIGURE 3 is generally similar to (that shown in\FIGURE 1 except that the bottom 21 is offset downwardly. The top flangeportion 22 is connected to the bottom 21 by side walls generally shownat 23, 24, 25 and 26. The intermediate portions of the side walls arepreferably provided with reinforcing, upwandly extending grooves 27(FIGURE 4) similar to the grooves 8 in FIGURE 2. The inwardly extendingindentations 28, 29, 30 and 31 at the corners are similar to theindentations 9, 10, 11 and 12in FIGURE 1. Each corner is also preferablyrounded and provided with adjacent indentations 32, 33, 34, 35, 36, 37,38 and 39 which extend part way from the top toward the bottom and curveaway from the corner indentation.

As will be seen from FIGURES 5, 6 and 7, the corner indentationspreferably taper and form a sharper angle at 40 near the top of thecontainer than at 41 near the bottom. FIGURE 7 illustrates the manner inwhich the indentations adjacent the corner indentation curve in thepreferred practice of the invention. The combination of the cornerindentations which fall in a straight vertical plane and the adjacentindentations which fall in a curved vertical plane assists in restoringthe plastic material to 3 its original position when the corners andareas adjacent the corners are pressed inwardly.

It will be understood that the invention is directed primarily towardcontainers made from plastic materials which are relatively rigid butare distortable and at the same time have enough resilience to return totheir original positions. While the invention is especially desirabletor the manufacture of containers made from oriented polystyrene it canalso be used to manufacture containers irom high impact polystyrene andother plastic materials having the general properties previouslydescribed. The shape (of the container is not particularly important solong as it has corners. It may, for example, have three, EfOflll, five,six, seven, or eight sides. However, most of the containers of this typeare rec tangnlar or four-sided.

The invention provides a container or receptacle which is especiallyuseful in packaging food because or its ability to retain its shapeunder ordinary conditions of storage and handling and to restore it toits original shape when distonted by unusual external pressures.

The invention is hereby claimed as follows:

1. A container of selfsustaining, relatively rigid, resilient,distortable plastic material comprising a bottom and side wallsextending upwardly therefrom, corners formed between adjacent side Wallsof said container, each corner having a central inwardly extendinggroove on a line substantially bisecting said corner and extending alongat least a portion of the vertical height of the side Walls tosubstantially adjacent the bottom of said container and first and secondinwardly extending adjacent grooves each spaced from said central grooveand located on opposite sides of said central extending groove in theside walls leading to said corner and running along at least a portionof the vertical height of the side Walls toward the bottom of saidcontainer in the respective side walls, said adjacent grooves curvingrespectively away from the central groove as they approach the bottom ofsaid container.

2. The container set forth in claim 1 wherein the side walls extendradially outwardly tfirorn the bottom wall and the central groove in thecorner has a curvilinear portion along the vertical height thereof. 1

3. The container set fonth in claim 1 wherein the said adjacent groovesterminate short of the vertical plane of the lower termination :of saidcentral groove.

4. The container set forth in claim 1 wherein the central groove mergesWith the bottom of the container.

5. The container set forth in claim 1 wherein the central groove has avarying width as measured at the mouth and along the vertical extentthereof, the groove being narrower adjacent the bottom ot the container.

6. The container set forth in claim 1 which is turther characterized asbeing generally rectilinear in configuration, the periphery of thecontainer adjacent the top having a greater dimension than the peripheryadjacent the bottom, the side walls being stepped adjacent the bottom,the central and adjacent grooves terminating at.

the step portions of the side wall.

7. The container set forth in claim 1 wherein said central inwardlyextending tgroove extends from the top of the container to substantiallyadjacent the bottom of the container.

8. A container of sold-sustaining, relatively rigid, resilient,distortable plastic material comprising a bottom and side wallsextending upwardly therefrom, cornersformed between adjacent side wallsor said container, each corner having a central inwardly extendinggroove on a line bisecting said corner and extending along at least apor tion of the vertical height of the side walls to the bottom of saidcontainer, a plurality of grooves in each of said adjacent side wallsspaced from said central groove in said corner, at least said cornergroove extending radially inwardly adjacent the lower terminus thereoftor a dis: creet distance into the plane of said bottom wall and at arelatively large angle to the major plane of said side walls, first andsecond areas of said container immediately adjacent and on oppositesides of said central groove References Cited in the file of this patentUNITED STATES PATENTS 2,738,915 St. Clair Mar. 20,1956

FOREIGN PATENTS 58,857 tFrance Apr. 6, 1954

1. A CONTAINER OF SELF-SUSTAINING, RELATIVELY RIGID, RESILIENT,DISTORTABLE PLASTIC MATERIAL COMPRISING A BOTTOM AND SIDE WALLSEXTENDING UPWARDLY THEREFROM, CORNERS FORMED BETWEEN ADJACENT SIDE WALLSOF SAID CONTAINER, EACH CORNER HAVING A CENTRAL INWARDLY EXTENDINGGROOVE ON A LINE SUBSTANTIALLY BISECTING SAID CORNER AND EXTENDING ALONGAT LAST A PORTION OF THE VERTICAL HEIGHT OF THE SIDE WALLS TOSUBSTANTIALLY ADJACENT THE BOTTOM OF SAID CONTAINER AND